The various working sections of an agricultural combine may be said to comprise three sections: a forwardly positioned header section which carries a cutterbar and knife for harvesting the crop, a platform for raking the crop toward the cutterbar and knife, and an auger associated with the platform for combining and feeding the harvested crop on the platform rearwardly; an intermediate feeder section for conveying the crop rearwardly from the header to a threshing section; and a thresher in the thresher section for separating the main edible crop from the remaining plant parts. For efficient harvesting of low growing crops, it is, of course, desirable to have the cutterbar and knife follow as close as possible to the contour of the ground without jamming or digging into the soil.
In general, the header section of a combine may be considered to be a comparatively rigid structure. However, the cutterbar and knife carried by the header are characterized by a limited flexibility related to the materials of construction and the size of the combine and transverse width of the header.
It is well known to provide a combine header with bottom shoes or skids which ride on the ground and support the knife thereabove for performance of its cutting operation. An example of such structure may be seen in U.S. Pat. No. 1,881,411 which discloses individual shoes spaced along the width of the cutter frame. A drawback to the individual shoe arrangement taught by the patent was that the cutter was undesirably row sensitive. For example, if one of the shoes was riding in a groove or depression between crop rows, the limited flexibility of the cutter frame might cause the cutter to tilt upwardly.
More recently, cutterbar assemblies have been provided with a continuous skid which spans substantially the full width of the header. While those arrangements eliminated the problems of row sensitivity, they reduced the flexibility of the cutterbar thereby interfering with the cutterbar's ability to follow the contour of the ground. In addition, the continuous skids added appreciably to the weight of the cutterbar assembly.
There thus exists a need for a cutterbar assembly which retains it desirable characteristics of flexibility but is nonetheless not row sensitive. Similarly, there exists a need for a flexible cutterbar assembly which is efficient and durable but nonetheless reduces the overall weight of the cutterbar.